"Social norms are primitive and elemental," says Dr. Robert Cialdini, author of Influence: The Psychology of Persuasion.

Robert Pattinson, the star of the Twlight film franchise, has been named one of the most powerful celebrities in the world after appearing on the Forbes list for the first time.

In his book Influence, Robert Cialdini describes this as a "request + reason" and proves that this combination significantly increases the likelihood that your request will be obliged.